Rinkitink in Oz

Rinkitink in Oz
by L. Frank Baum (1856-1919)

Prince Inga lives a happy life on the island of Pingaree until one day invaders from the north enslave every person on the island, including his parents. Inga, who escaped unnoticed in an apple tree, visiting King Rinkitink who had fallen in a well, and surly talking donkey Bilbil embark on a quest to save the Pingareeans.
Armed only with three magic pearls that imbue strength, invincibility, and wisdom, the three take on the open sea, the military might of the islands of Regos and Coregos, and the Nome King.
(Summary by Scott Sherris)